John of Austria (1547-1578), the illegitimate half-brother of King Philip II of Spain, distinguished himself as a military commander, notably at the Battle of Lepanto.

The most powerful man in Western Europe in the first half of the 16th century was the Holy Roman Emperor, Charles V. As King Charles I of Spain, he inherited from his grandparents Ferdinand and Isabella, great wealth and importance in both the Old World and the New. Most of Charles's adult life was spent, however, responding to crises which arose in his German lands as a result of the Protestant Reformation and an accompanying movement for greater local independence from the Empire. Confronted by the challenge of the Schmalkaldic League, a union of princes determined to resist imperial power, Charles traveled in April 1546, to Regensburg, for a meeting of the Diet (imperial parliament) where he hoped to recruit allies for a war...